US 20090299393 A1
The devices and methods described herein relate to improved structures for removing obstructions from body lumens. Such devices have applicability in through-out the body, including clearing of blockages within the vasculature, by addressing the frictional resistance on the obstruction prior to attempting to translate and/or mobilize the obstruction within the body lumen
1. A medical device for removing an obstruction from a blood vessel, the medical device comprising:
a main bundle comprising a group of wires having a first end and a second end;
a capturing portion formed by the group of wires and having a translating surface adjacent to a capturing surface, the translating surface having an open proximal end and the capturing surface having a permeable distal end;
where the capturing portion is formed from the group of wires such that the group of wires diverges from the second end of the main bundle to form the permeable distal end, the group of wires extend back in a proximal direction to form the capturing surface, the translating surface, and open proximal end about the main bundle; and
where the translating surface and capturing surface are configured so that a translating surface axial strength is greater than a capturing surface axial strength, wherein application of a tensile force on the main bundle causes axial compression of the capturing surface without causing axial compression and deformation of the translating surface sufficient to deform the translating surface as the capturing portion engages the obstruction.
2. The medical device of
3. The medical device of
4. The medical device of
5. The medical device of
6. The medical device of
7. The medical device of
8. The medical device of
9. The medical device of
10. The medical device of
11. The medical device of
12. The medical device of
13. The medical device of
14. The medical device of
15. The medical device of
16. The medical device of
17. The medical device of
18. The medical device of
19. The medical device of
20. The medical device of
21. The medical device of
22. The medical device of
23. The medical device of
24. The medical device of
25. The medical device of
26. A retrieval device for removing an obstruction from a body lumen, the retrieval device comprising:
at least one leading wire;
a retrieval body comprising a translating section adjacent to a capturing section, the translating section having an open proximal end and the capturing section having a permeable distal end, where the leading wire extends to a portion of the capturing section to permit articulation of the open proximal end relative to the leading wire; and
where the translating section and capturing section are configured so that a translating section axial strength is greater than a capturing section axial strength, wherein application of a tensile force on the leading wire causes axial compression of the capturing surface without causing axial deformation of the translating surface when the retrieval body engages the obstruction.
65. A method of removing an obstruction from a blood vessel, the method comprising:
advancing a catheter distal to the obstruction;
deploying a first capturing portion distal of the obstruction, where the first capturing portion comprises a translating surface and a capturing surface, the translating surface having an open proximal end and the capturing surface having a permeable distal end, and at least one leading wire affixed to the capturing surface and extending through the capturing portion and through the catheter, where the translating surface and capturing surface are configured so that a translating surface axial strength is greater than that of a capturing surface axial strength;
proximally moving the leading wire to compress the capturing surface without compressing the translating surface sufficient to cause axial deformation of the translating surface such that the translating surface gradually advances over the obstruction; and
removing the obstruction and first capturing portion from the blood vessel.
77. A reentry device for withdrawing an object into a distal end of a sheath, the reentry device comprising:
a elongate member having a distal portion and a lumen extending therethrough; and
a plurality of first tines arranged circumferentially at the distal portion, the plurality of first tines each having a distal end forming a first discontinuous funnel where the distal end of each first tine is spaced from the distal end of an adjacent first tine, wherein the first discontinuous funnel is collapsible upon withdrawal into the distal end of the sheath.
86. A reentry device for withdrawing an object into a distal end of a sheath, the reentry device comprising:
an elongate member having a distal portion and a lumen extending therethrough, the elongate member sized to slidably fit within the sheath;
a first slotted funnel comprising a plurality of first tines each having free ends discontinuous with free ends of adjacent first tines, where the first slotted funnel is collapsible upon withdrawal into the distal end of the sheath; and
a second funnel located proximal to the free ends of the first tines.
94. A retrieval system for withdrawing an object into a distal end of a sheath, the retrieval system comprising:
an elongate member having a distal portion and a lumen extending therethrough;
a flexible layer having a portion affixed to the elongate member, where a first end of the flexible layer is configured to form a funnel at the distal portion of the elongate member;
a retrieval device advanceable through the elongate member for engaging the object, where proximal movement of the retrieval device into the flexible causes the flexible layer to engage the retrieval device to assist the retrieval device securing the object to the sheath.
107. A system for removing a object within a body, the system device comprising:
a sheath having a sheath distal end and a sheath lumen extending therethrough; a reentry device slidably located in the sheath lumen and being advanceable out of the sheath distal end, the reentry device comprising an elongate member having a first slotted funnel and a second slotted funnel, the elongate member having a distal portion and a lumen extending therethrough and being sized to slidably fit within the sheath,
the first slotted funnel and the second slotted funnel each respectively comprising a plurality of first and second tines, each of the tines having a free end discontinuous with the free ends of an adjacent tines, where a distal end of the second slotted funnel is proximal to a distal end of the first slotted funnel and where the first and second tines are rotationally offset such that upon withdrawal into the sheath, the second tines cover a portion off a space between adjacent first tines.
This application is a non-provisional application of U.S. Provisional Application No. 61/016,651 filed on Dec. 26, 2007, the entirety of which is incorporated by reference herein.
The devices described herein are intended to retrieve obstructions from the body. In a first variation, the devices are constructed in wire form where the wires diverge from a main bundle to form a variety of shapes that form a composite device. The benefit of such a diverging wire construction is that the composite complex device can be of a “joint-less” construction. Such devices have applicability through out the body, including clearing of blockages within body lumens, such as the vasculature, by providing a capturing portion that can envelop the obstruction to address the frictional resistance between the obstruction and body lumen prior to attempting to translate and/or mobilize the obstruction within the body lumen. In addition, the devices described below include features that prevent unwanted and premature mobilization of the obstruction when removing the obstruction through tortuous anatomy.
Many medical device applications require advancement of device in a reduced profile to a remote site within the body, where on reaching a target site the device assumes or is deployed into a relatively larger profile. Applications in the cerebral vasculature are one such example of medical procedures where a catheter advances from a remote part of the body (typically a leg) through the vasculature and into the cerebral region of the vasculature to deploy a device. Accordingly, the deployed devices must be capable of achieving a larger profile while being able to fit within a small catheter or microcatheter. In addition, the degree to which a physician is limited in accessing remote regions of the cerebral vasculature is directly related to the limited ability of the device to constrain into a reduced profile for delivery.
Treatment of ischemic stroke is one such area where a need remains to deliver a device in a reduced profile and deploy the device to ultimately remove a blockage in an artery leading to the brain. Left untreated, the blockage causes a lack of supply of oxygen and nutrients to the brain tissue. The brain relies on its arteries to supply oxygenated blood from the heart and lungs. The blood returning from the brain carries carbon dioxide and cellular waste. Blockages that interfere with this supply eventually cause the brain tissue to stop functioning. If the disruption in supply occurs for a sufficient amount of time, the continued lack of nutrients and oxygen causes irreversible cell death (infarction). Accordingly, immediate medical treatment of an ischemic stroke is critical for the recovery of a patient.
Naturally, areas outside of ischemic stroke applications can also benefit from improved devices. Such improved devices can assume a profile for ultimate delivery to remote regions of the body and can remove obstructions. There also remains a need for devices and systems that can safely remove the obstruction from the body once they are secured within the device at the target site. Furthermore, there remains a need for such devices that are able to safely removed once deployed distally to the obstructions in the even that the obstructions is unable to be retrieved.
Accordingly, a need remains for devices that can assume deployed configurations and are fabricated to eliminate or reduce the number of joints and/or connection points in the device.
The examples discussed herein show the inventive device in a form that is suitable to retrieve obstructions or clots within the vasculature. The term obstructions may include blood clot, plaque, cholesterol, thrombus, naturally occurring foreign bodies (i.e., a part of the body that is lodged within the lumen), a non-naturally occurring foreign body (i.e., a portion of a medical device or other non-naturally occurring substance lodged within the lumen.) However, the devices are not limited to such applications and can apply to any number of medical applications where elimination or reduction of the number of connection points is desired.
One variation of the device includes a medical device for removing an obstruction from a blood vessel, the medical device comprises a main bundle comprising a group of wires having a first end and a second end, a capturing portion formed by the group of wires and having a translating surface adjacent to a capturing surface, the translating surface having an open proximal end and the capturing surface having a permeable distal end, where the capturing portion is formed from the group of wires such that the group of wires diverges from the second end of the main bundle to form the permeable distal end, the group of wires extend back in a proximal direction to form the capturing surface, the translating surface, and open proximal end about the main bundle; and where the translating surface and capturing surface are configured so that a translating surface axial strength is greater than a capturing surface axial strength, wherein application of a tensile force on the main bundle causes axial compression of the capturing surface without causing axial compression and deformation of the translating surface sufficient to deform the translating surface as the capturing portion engages the obstruction.
The medical device can include a capturing surface that is configured to generate a spring force against the translating surface when a proximal force applied by the main bundle of wires compresses the capturing surface against the translating surface when encountering resistance from the obstruction, where the capturing surface is configured to have a sufficient axial stiffness to direct the spring force and proximal force to the open proximal end as the open proximal end engages the obstruction where the capturing surface is also sufficiently flexible to conform to a shape of the vessel.
In another variation, the capturing section is configured so that when the open proximal end of the translating section engages resistance equal to or greater than a threshold force, proximal movement of the leading wire inverts the capturing section within the translating section and reduces a size of the capturing section to enable the capturing section to re-enter a catheter.
In those variation of the device that are navigated in tortuous anatomy (such as the cerebral vasculature), the device can include a main bundle joined to a proximal bundle, where the proximal bundle comprises a stiffness greater than the main bundle and where the main bundle extends for at least a predetermined range from the permeable distal end to allow navigation of a distal portion of the medical device within the cerebral vasculature.
Another variation of the device includes a retrieval device for removing an obstruction from a body lumen, the system comprising at least one leading wire; a retrieval body comprising a translating section adjacent to a capturing section, the translating section having an open proximal end and the capturing section having a permeable distal end, where the leading wire is extends to a portion of the capturing section to permit articulation of the open proximal end relative to the leading wire; and where the translating section and capturing section are configured so that a translating section axial strength is greater than a capturing section axial strength, wherein application of a tensile force on the leading wire causes axial compression of the capturing surface without causing axial deformation of the translating surface when the retrieval body engages the obstruction.
Variations of the retrieval system can also include a sheath having a hub located at a proximal end, a proximal capture portion affixed to a distal end of the sheath, at least one leading wire extending through the sheath, where a distal section of the leading wire comprises a distal stiffness and where a proximal section of the leading wire comprises a proximal stiffness, where the proximal stiffness is greater than the distal stiffness, a distal capturing portion at the distal end of the leading wire, the distal capturing portion being axially moveable relative to the proximal capture portion, and an insertion tool slidably located over the sheath, the insertion tool comprising a gripping region affixed to a rigid section, where compression of the gripping portion creates a frictional fit between the insertion tool such that when the insertion tool is coupled to the catheter, compression of the gripping portion and axial movement of the insertion tool advances the sheath within the catheter.
In one variation of the devices described herein, the device comprises a main bundle or group of wires that diverge to form a device having various shapes but few or no connections points or joints (where fabrication of such a construction is referred to as “jointless”). Clearly, the inventive devices described herein are not limited to such a jointless construction. Additional variation includes one or more leading wires that are attached to a capturing portion as described below.
In another variation, the device includes a main bundle comprising one or a group of wires. The device also includes a capturing portion formed by the wires or wire of the main bundle. The capturing portion includes a cavity or space that is able to surround the obstruction. Accordingly, the capturing portion includes an open proximal end, a permeable distal end, and a capturing surface extending therebetween. The permeable distal end should be sufficiently permeable to allow blood to flow but have sufficient surface area to prevent escape of the obstruction or to prevent particles such as pieces of clot or emboli that would otherwise cause a complication if such pieces migrate through the body. In some variations of the device, the capturing portion is formed from the group of wires such that the group of wires diverges from the second end of the main bundle to form the permeable distal end, the group of wires extend back in a proximal direction to form the capturing surface and open proximal end about the main bundle. Although some closing of the open proximal end can occur, it will not be sufficient to interfere with the obstruction as the capturing portion moves over the obstruction. In some variations, the permeable end may be the distal end or be towards the distal end (meaning anywhere past a proximal end). The terms distal and proximal are relative to the physician (e.g., the distal end is the farthest end from the catheter/physician).
The devices of the present invention typically include a main bundle from which the wires extend. In most case, the main bundle extends for a length sufficient to withdraw the device from a body of a patient. Accordingly, in such cases, the main bundle shall extend through the length of a catheter. In alternate constructions, the main bundle may be affixed to a single wire or member. In such cases, a main bundle does not extend from the capturing portion to the exterior of the patient. Instead, a single wire extends to the operator interface of the device where the wire is affixed to a main bundle.
Devices of the present invention can incorporate any number of wires of different characteristics including, but not limited to, materials, shapes, sizes and/or diameters. Clearly, the number of permutations of device configurations is significant. Providing devices with such a composite construction allows for the manipulation of the device's properties to suite the intended application.
In an additional variation, the surface of the capturing portion can include a wire frame structure, a mesh, a single wound wire, a film, a membrane, a polymer covering, and a plurality of crossing wires or a heterogeneous mixing of these. In additional variations, a section of the capturing portion can include wires, while another section of the capturing portion can include a film. Clearly, any number of permutations is within the scope of this disclosure. In any case, the capturing surface should prevent the obstruction from escaping as the device is removed from the body. Clearly, the capturing surface can comprise any number of shapes or configurations.
As noted herein, the joint-less construction improves the flexibility and strength of the device by eliminating joints, connection points, or other attachment points. In addition, the joint-less construction improves the ability of the device to be delivered through a small microcatheter. As a result, the device and microcatheter are able to access remote regions of the vasculature.
The devices may be fabricated to be self-expanding upon deployment from a catheter. Alternatively, the devices can be constructed from shape-memory alloys such that they automatically deploy upon reaching a pre-determined transition temperature.
The devices of the present invention may also include features to prevent migration of the obstruction as the capturing portion encapsulates the obstruction. For example, a proximal foot (such as region of increased surface area) can be located on or in the catheter. In another variation, an additional capture portion is located on the catheter where the proximal end of this capture is a mesh, a single wound wire, a film, a membrane, a polymer covering, or a plurality of crossing wires affixed to or in the catheter. Accordingly, the capturing portions both envelope or surround the obstruction as they are moved together. As noted below, additional variations may allow for temporarily locking of the two capturing portions together for increase effectiveness in removing the obstruction from the body.
The capturing portions disclosed herein can include mechanical features that assist in removal of the obstruction. These features can be hooks, fibers, barb, or any such structure. Any portion of the capturing portion or even the device can have such hooks, fibers, or barbs that grip into the obstruction as the device surrounds the obstruction. It will be important that such features prevent the obstruction from sliding proximally but do not hinder the ability of the practitioner to remove the device from the body.
The operation of the devices and method described herein secure the obstruction, overcome the friction forces acting on the obstruction, and then remove the obstruction from the anatomy without losing or fractionating the obstruction. In a first variation, the inventive method includes advancing a catheter distal to the obstruction, deploying a first capturing portion distal of the obstruction, where the first capturing portion comprises a translating surface and a capturing surface, the translating surface having an open proximal end and the capturing surface having a permeable distal end, and at least one leading wire affixed to the capturing surface and extending through the capturing portion and through the catheter, where the translating surface and capturing surface are configured so that a translating surface axial strength is greater than that of a capturing surface axial strength, proximally moving the leading wire to compress the capturing surface without compressing the translating surface such that the translating surface gradually advances over the obstruction, and removing the obstruction and first-capturing portion from the blood vessel
Additional variations of the method include (1) passing a catheter distally to the obstruction by passing either through the obstruction and/or between the obstruction and the vascular wall; (2) deploying a first capturing portion distally to the obstruction and the catheter is withdrawn proximal to the obstruction; (3) the capturing portion is then translated over the obstruction by withdrawing the main bundle. Since the main bundle is affixed to a distal end of the capturing portion, misalignment between the bundle and the capturing portion does not cause distortion of the open proximal end. Since the open proximal end remains expanded against the lumen wall, the capturing portion can then be advanced over the obstruction.
The method and systems may also include the use of an additional capturing portion having an open distal end. This configuration allows the first capturing portion and second capturing portion to envelop or ensnare the obstruction from both the proximal and distal sides. Additional variations even allow for temporarily locking the two capturing portions together. Such a feature increases the ability to remove the obstruction from the body
It should be noted that reference to surrounding, capturing or securing the obstruction includes partially and/or fully surrounding, engulfing, encapsulating, and/or securing the obstruction. In any case, a portion of the device engages the obstruction prior to translation of the obstruction within the lumen.
It should be noted that in some variations of the invention, all or some of the device can be designed to increase their ability to adhere to the obstruction. For example, the wires may be coupled to an energy source (e.g., RF, ultrasonic, or thermal energy) to “weld” to the obstruction. Application of energy to the device can allow the surrounding portion to deform into the obstruction and “embed” within the obstruction. Alternatively, the device can impart a positive charge to the obstruction to partially liquefy the obstruction sufficiently to allow for easier removal. In another variation, a negative charge could be applied to further build thrombus and nest the device for better pulling force. The wires can be made stickier by use of a hydrophilic substance(s), or by chemicals that would generate a chemical bond to the surface of the obstruction. Alternatively, the filaments may reduce the temperature of the obstruction to congeal or adhere to the obstruction.
Additional variations of the invention include a reentry device for withdrawing an object into a distal end of a sheath, the reentry device comprising a elongate member having a distal portion and a lumen extending therethrough, a plurality of first tines arranged circumferentially at the distal portion, the plurality of first tines each having a distal end forming a first discontinuous funnel where the distal end of each first tine is spaced from the distal end of an adjacent first tine, wherein the first discontinuous funnel is collapsible upon withdrawal into the distal end of the sheath, a second funnel spaced proximal to the first funnel, where the second funnel is collapsible upon withdrawal into the distal end of the sheath, and wherein a distal perimeter of the first discontinuous funnel shape is distal to a distal perimeter of the second funnel.
In an additional variation, the second funnel comprises a plurality of second tines arranged circumferentially at the distal portion, the plurality of second tines each having a distal end forming a second discontinuous funnel shape where the distal end of each second tine is spaced from the distal end of an adjacent second tine.
Another example of a reentry device includes an elongate member having a distal portion and a lumen extending therethrough, the elongate member sized to slidably fit within the sheath, a first slotted funnel comprising a plurality of first tines each having free ends discontinuous with free ends of adjacent first tines, where the first slotted funnel is collapsible upon withdrawal into the distal end of the sheath; and a second funnel located proximal to the free ends of the first tines.
The reentry device can also comprises a retrieval system for withdrawing an object into a distal end of a sheath. The term sheath, when used with a reentry device, is intended to include any tube, introducer, sheath, or access device. Typically, when the retrieval device is used with neurovascular retrieval devices, the sheath will be a femoral access sheath or device. Regardless, the reentry device includes a first elongate member having a distal portion and a lumen extending therethrough, a second elongate shaft extending through the first elongate member, a flexible layer having a first end inverted on a distal end of the second elongate shaft and a second end affixed to an exterior of the first elongated shaft, where decreasing a distance between the distal end of the second elongate shaft and the exterior of the first elongated member causes the flexible material to form a funnel when the flexible layer further inverts about the second elongate shaft.
Additional devices and methods for treating ischemic stroke are discussed in commonly assigned U.S. patent application Ser. Nos.: 11/671,450 filed Feb. 5, 2007; 11/684,521 filed Mar. 9, 2007; 11/684,535 filed Mar. 9, 2007; 11/684,541 filed Mar. 9, 2007; 11/684,546 filed Mar. 9, 2007; 11/684,982 filed Mar. 12, 2007, 11/736,526 filed Apr. 17, 2007, 11/736,537 filed Apr. 17, 2007, and 11/825,975 filed Sep. 10, 2007; the entirety of each of which is incorporated by reference. The principles of the invention as discussed herein may be applied to the above referenced cases to produce devices useful in treating ischemic stroke. In other words, the wire-shaped construction of devices according to present invention may assume the shapes disclosed in the above-referenced cases when such a combination is not inconsistent with the features described herein.
Each of the following figures diagrammatically illustrates aspects of the invention. Variation of the invention from the aspects shown in the figures is contemplated.
It is understood that the examples below discuss uses in the cerebral vasculature (namely the arteries). However, unless specifically noted, variations of the device and method are not limited to use in the cerebral vasculature. Instead, the invention may have applicability in various parts of the body. Moreover, the invention may be used in various procedures where the benefits of the method and/or device are desired.
It is noted that any number of catheters or microcatheters may be used to locate the catheter/microcatheter 12 carrying the obstruction removal device 200 at the desired target site. Such techniques are well understood standard interventional catheterization techniques. Furthermore, the catheter 12 may be coupled to auxiliary or support components 14, 16 (e.g., energy controllers, power supplies, actuators for movement of the device(s), vacuum sources, inflation sources, sources for therapeutic substances, pressure monitoring, flow monitoring, various bio-chemical sensors, bio-chemical substance, etc.) Again, such components are within the scope of the system 10 described herein.
In addition, devices of the present invention may be packaged in kits including the components discussed above along with guiding catheters, various devices that assist in the stabilization or removal of the obstruction (e.g., proximal-assist devices that holds the proximal end of the obstruction in place preventing it from straying during removal or assisting in the removal of the obstruction), balloon-tipped guide catheters, dilators, etc.
As shown, the device 200 includes a main bundle 202 comprising a group of individual leading wires 204. In this variation, the bundle of leading wires 204 is surrounded by a coil or coiled wire 205. The coiled wire 205 can comprise a single leading wire that joins the device 202. Alternatively, the coiled wire 205 can extend terminate or wrap back prior to forming the capture portion 226. Moreover, the coiled wire 205 can extend throughout a length the main bundle 202, or along one or more segments of the main bundle 202.
While the example shows the group consisting of four individual leading wires 204, the bundle 202 can have any number of leading wires. In various examples 2, 4, or 8 wires were used to construct the device. In certain variations, the number of wires in the main bundle loop around from the capturing portion. For example, if 2 leading wires are used to construct the device, then when constructing the main bundle 202 2 wires are set to extend distally towards the capturing portion, where the 2 wires are then shaped to form the capturing portion. Eventually, the wires then loop back to extend proximally away from the capturing portion. Therefore, the 2 wires are doubled in the main bundle to create 4 separate wires in the main bundle.
The individual wires 204 themselves may be comprised of a number of different “micro” filaments, wires, or a single type of wire. Variations of the wires 204 are discussed in detail below; however, the wires 204 can be strands, filaments, or any similar structure that is able to be joined to form the device. The bundle 202 may be braided, wrapped, twisted, or joined in any manner such that they do not separate or become unbundled except where desired. For example, wires in any section of the device 200 can be bonded together (e.g., with epoxy, a polymeric coating, weld, solder, and/or adhesive, etc.) to prevent the wires from separating during deformation of the device as it deploys or removes the obstruction. In addition, the main bundle 202 can incorporate any number of features to assist in orienting the device 200 within the body passage. For example, the main bundle 202 can include a pre-set bend that would bias the capturing portion 226 in a desired orientation upon deployment as discussed below.
As also discussed below, variations of the present device 200 include capturing portions 226 where the translating section 234 provides a greater axial strength than an axial strength of the capturing section 232. The axial strength (e.g., column strength) determines whether the respective section of the capturing portion 226 compresses when the device 200 encounters resistance from an object and as a proximal or pulling force is applied through the main bundle or leading wire 202. In use, the translating section 234 resists axial compression and deformation so that it can locate about the obstruction. While the nature of moving the translating section will place the structure in a state of compression, there will be no visible deformation or deflection that prevents the translating section from advancing across an obstruction.
There are a number of approaches to adjust the axial strength of a capturing section 232 as well as the entire structure. In a first example, the manner in which the leading wire is wound to form the respective surface 232, 234 impact the respective axial strength. As shown, the traversing section 234 comprises a series of wrapped wires extending in an axial direction. This axial alignment causes the wires to oppose axial forces and thus increases the axial strength of the traversing section 234 relative to the capturing section 232. In the latter section, the wires 232 extend in a helical direction about the section 232. Thus there is less resistance to an axial load when compared to the traversing section 234.
Alternatively, or in combination, additional techniques can produce a device 200 with a capturing portion 226 that has sections of varying axial strength. In one example, the wire diameter can be adjusted to produce the desired column strength. Generally, for a given construction, a larger diameter wire increases the column strength of the section. In addition, larger diameter leading wires can terminate at the translating section 234 to permit smaller diameter wires to form the capturing section 232. In another example, the leading wire 204 composition can be selected to produce the desired axial strength. For example, drawn filled tube (DFT) wire has 30% platinum 70% nitenol. Decreasing the amount of platinum and increasing the nitenol increases the wire strength and results in higher column strength. In yet another example, the respective section, or the entire capturing portion 226, can be processed to produce the desired axial strength. For example, changing the annealing profile (e.g., temp, time) affects the wire strength, and therefore the axial strength.
Variations of devices 200 described herein can have capturing portions with alternate configurations than those shown in above. The capturing portion 226 can include constructional designs such as a basket, a filter, a bag, a coil, a helical wire structure, a mesh, a single wound wire, a film, a membrane, a polymer covering, or a plurality of crossing wires. In variations of the device, the capturing portion 226 is sufficiently permeable to allow blood or other fluid flow therethrough. As noted above, capturing portion 226 may be any structure that covers, encapsulates, engulfs, and/or ensnares the obstruction either fully or partially. Accordingly, although the capturing portion 226 is illustrated as a filter/bag, the wires may diverge to form a coil, helical shape, other mesh structure, or any other structure that defines a space that can be translated over the obstruction to ultimately remove the obstruction 2.
The capturing portion 226 can include an open proximal end 228, a permeable distal end 230 and a capturing surface 232 located therebetween. The capturing surface 232 of the capturing portion 226 defines a volume, cavity, or space that is able to cover, encapsulate, envelop, engulf, ensnare and/or surround the obstruction. Generally, the term traversing wire or filament refers to the section of leading wire 204 that forms the traversing surface 238. Generally, the traversing wires form the capturing surface 238 and then form the open proximal end 228. As discussed herein and illustrated below, the open proximal end 228 expands within the lumen, typically to the lumen walls, so that the obstruction enters the open proximal end 228 as the bundle 202 (or leading wire) translates the device 200 proximally.
The permeable distal end 230 is typically sufficiently porous so that fluid or blood may flow through. However, the end 230 is sufficiently closed (or has an increased surface area) so that the obstruction should not escape through the distal end 230 of the device 200. This construction typically causes the obstruction to become ensnared within the capturing portion 226 and prevented from passing through by the permeable distal end 230.
As shown in
Turning now to the construction of the device 200, as shown above, the main bundle or a leading wire 202 extends beyond the open proximal end 228 and forms the capturing portion. In one variation, the construction of the device relies on converging/diverging wires to form continuous shapes so that the device is completely joint or connection free. However, as noted herein, the leading wire or main bundle 202 can be affixed to a structure that forms the capturing portion via an attachment point, joint, or junction. In addition, the structures forming the capturing portion can be fabricated from such processes as laser cutting of tubes, etching, metal injection molding, or any other such process.
The devices of the present invention can also include additional features to aid in removal of obstructions. For example, as shown in
In additional variations, the main bundle can diverge to form the capturing portion in multiple locations so long as the capturing portion's ability to articulate is not sacrificed. For example, the main bundle can diverge in several locations along the capturing surface (not shown).
In addition to the reinforcement ring 240,
As shown in
Naturally, the divergence of the wires can occur over a length of the capturing portion 226 rather than immediately at the distal end. For example, as show in FIG. 3D, the wires diverge towards a mid-section of the capturing portion and ultimately form the permeable distal end 230.
In some variations, the leading wire can extend to the proximal end of the system for manipulation by the physician. However, it is often the case that the characteristics of the device must vary along its length. For example, when the device is intended for use in remote tortuous anatomy, the proximal section of the device is desirably stiffer (to advance the distal portion of the device to the target anatomy). However, the distal section of the device must have properties that make it suitable for the tortuous anatomy. In the case where devices are used in the cerebral vasculature, the distal section must be extremely flexible, while the proximal section should be stiff. In many cases, different material properties are required. A problem then arises in attempting to join different materials especially in the joining region.
Conventional joining methods include soldering, welding, gluing, thermal junctions, etc. These joining methods produce an area having an increase in the stiffness of the device. For example, if two wires are to be laser welded together, then the section where they are joined has an overlap which yields greater stiffness than the rest of the wire. This increased area of stiffness is often balanced against the strength of the joined segment. If the joined region is too long, the strength will be sufficient but the increase in stiffness often prevents navigation through the tortuous anatomy. IF the joined region is too short, then the device can navigate through the anatomy but the bond is weaker and a risk of failure increases.
The device may include a number of radiopaque wires, such as gold and platinum for improved visibility under fluoroscopic imaging. In other words, any combination of materials may be incorporated into the device. In addition to the materials, the size of the wires may vary as needed. For example, the diameters of the wires may be the same or may vary as needed.
In addition, the individual wires may have cross-sectional shapes ranging from circular, oval, d-shaped, rectangular shape, etc.
To illustrate one such example, a device can have 8-12 wires made of 0.003″ round superelastic material (e.g., nitinol). The device may additionally have 2-4 wires made from 0.002″ platinum for fluoroscopy. Of the 8-12 nitinol wires, 1-4 of these wires can be made of a larger diameter or different cross-section to increase the overall strength of the device. Finally, a couple of polymer fibers can be added where the fibers have a desired surface property for clot adherence, etc. Such a combination of wires provides a composite device with properties not conventionally possible in view of other formation means (such as laser cutting or etching the shape from a tube or joining materials with welds, etc.). Clearly, any number of permutations is possible given the principles of the invention.
In another example, the device may be fabricated from wires formed from a polymeric material or composite blend of polymeric materials. The polymeric composite can be selected such that it is very floppy until it is exposed to either the body fluids and or some other delivered activator that causes the polymer to further polymerize or stiffen for strength. Various coatings could protect the polymer from further polymerizing before the device is properly placed. The coatings could provide a specific duration for placement (e.g., 5 minutes) after which the covering degrades or is activated with an agent (that doesn't affect the surrounding tissues) allowing the device to increase in stiffness so that it doesn't stretch as the thrombus is pulled out. For example, shape memory polymers would allow the device to increase in stiffness.
In another variation, one or more of the wires used in the device may comprise a Drawn Filled Tube (DFT) such as those provided by Fort Wayne Metals, Fort Wayne, Ind. As shown in
The size of the proximal foot 256 can be adjusted depending on the target site anatomy. For example, a larger surface area can be employed if the target site is within a bifurcation of the body passage. The size of the proximal foot 256 can also be adjustable during the procedure. For example, in the case of a petal/flange 258 configuration, the petals 258 can assume a larger size to initially stabilize the obstruction and then reduce in size to allow the obstruction to be completely engulfed by capturing section 226.
The proximal foot 256 can extend from an interior of the catheter 102, such as from within the internal lumen of the catheter, or from an additional lumen within a wall of the catheter. Alternatively, the proximal foot 256 can be permanently affixed to the catheter 102. In such a case, a separate catheter (without a proximal foot) can be employed to traverse the obstruction for deployment of the device distally to the obstruction. Once the device is deployed, the catheters can be exchanged to provide the proximal foot. In an additional variation, the proximal foot 256 can be affixed to a delivery sheath (as described below) and be collapsed within the catheter, where advancement out of the catheter expands the proximal foot 256 so that it may function as described above.
In an additional variation, a proximal capturing portion (as shown in
Variations of the device include additional structures, such as springs, hooks, barbs, etc, to cause the open ends 228 and 262 to interlock. As noted above, a separate catheter can be used to initially deploy the capturing portion 226 beyond the obstruction. Although the capturing portions shown have the same configuration, the capturing portions 226 and 260 used in any given system do not have to match in size, shape, and configuration. For example, the proximal capturing portion can be impermeable to flow while the distal capturing portion allows flow. In another example, one basket may be undersized relative to the other to improve nesting.
In any case, the construction of the system 10 shown in
As shown, the proximal end 264 can be compressed using a sheath 106 and/or catheter 102 However, other means of compressing may be employed (e.g., a loop structure, a tube over the sheath, a draw-string configuration, etc.) In use, once the distal capturing portion 226 is deployed distally to the obstruction 2 and the catheter 102 is withdrawn proximal to the obstruction 2, the proximal capturing portion 260 is deployed. As the proximal capturing portion 260 partially (or totally) engulfs the obstruction 2, the physician can collapse or compress the proximal capturing portion 260 to better secure the obstruction within the system 10.
It is noted that any number of shapes, configurations, as well as any number of joined wires may be contemplated to form devices under the present disclosure.
However, variations of the invention include selecting a number of wires to produce specific structural properties to the device. For example, the devices can have any number of wires where the limit is determined by the ability to produce a device of a sufficiently small size to access the area containing the obstruction. However, in some cases, it may be desired that wires are chosen to impart specified characteristics. For example, in the illustrated variation, the main bundle may comprise any number of wires that do not diverge to form subsequent shapes in the device. In other words, not all of the wires forming a section are required to diverge to form an adjacent section. Instead, these non-diverging wires may simply “loop” back away from the device. In an additional variation, one or more wires may diverge to form a particular portion of the capturing portion (e.g., the closed end, traversing wires, etc.). Then the wires can loop back to converge again with the main bundle.
Some variations of the device may be placed without an accompanying guidewire. Moreover, the structures discussed herein may be directly incorporated into a guidewire assembly where deployment may require a sheath or other covering to release the components from constraint.
However, as discussed above, there may be some procedures where the distal capturing portion 226 is deployed distal to an obstruction 2 that is deposited within the vessel or lumen such that a steady translation of the capturing portion 226 will not engulf the obstruction 2.
The construction described herein that allows for staged inversion of the capturing portion 2 provides a significant safety feature. A physician must undertake additional surgical intervention to remove any retrieval device that has become lodged distally to an immobile obstruction. The ability of staged inversion allows the physician to invert and remove the capturing portion 226 if application of a predetermined or threshold force is exceeded by proximal displacement of the device. This feature reduces the need for additional surgical intervention to remove a retrieval device that would otherwise become lodged or separated as a result of excessive forces being applied.
As also shown in the figure, the main bundle 202 and capturing portions become misaligned due to the tortuousity of the anatomy. However, because the capturing portions 226 and 260 are able to pivot or articulate relative to the main bundle 202 and catheter 102 or sheath 106, the open ends are able to remain against the lumen wall. In conventional devices where the open end is attached to either a wire or catheter, when the wire or catheter bends in the anatomy, the forces exerted on the open ends deform or distort the end to assume a reduced profile. Accordingly, the physician may have difficulty in removing an obstruction if the profile of the open end becomes reduced in size. Closing of the open end can also result in vascular damage if the physician applies too much force in translating the device.
The capturing portions described herein can include coverings or wrappings so long as the other features of the device are not impaired. Such coverings can be located on both capturing portions 226 and 260, only one or more capturing portions. The covering can include a strand or fiber wrapped or woven about the section, a polymer film, or a dipped polymer coating such as silicone, urethane, etc. The coating on either capturing portion can be solid or porous. In the latter case, blood can continue to flow through the coating. In one variation, the proximal capturing portion 260 could employ a solid covering while the distal capturing portion 200 could include a porous covering. In such a case, blood or other fluid flow could be temporarily halted by the presence of the solid covering to assist in removal of the obstruction.
Although the illustrated variation shown above comprise open-ended, circular, looped or partial loop shape cross sectional areas, variations of the capturing portions can include any number of shapes. For example, such a shape can include a circle, an arcuate shape, a partial circular shape, a loop, an oval, a square, a rectangle, a polygon, an overlapping loop, a pair of semi-circles, etc.) The various shapes may be heat set to be either self-expanding (i.e., superelastic) or the use of shape memory alloys can allow for the device to assume the particular shape upon reaching a desired transition temperature.
The exemplary shapes discussed above permit the shaped section to adjust in diameter in response to placement in varying diameters of body lumens. It is noted that a device may have different shaped sections on different ends of the device.
While many different shapes are contemplated to be within the scope of this disclosure, the shapes will depend upon the ultimate application of the device. As noted herein, the illustrated examples have particular applicability in retrieving obstructions from the vasculature. Accordingly, for these applications the shaped sections should form a shape so that they can expand against a vessel wall without causing trauma to the vessel. For example, upon release from the catheter, the shaped section can assume their resting shape and expand within the vessel. The resting shape can be constructed to have a size slightly greater than that of the vessel. Sizing the device relative to the target vessel may assist in placing the parts of the device against a vessel.
In an additional aspect, the shaped sections may be designed to have an unconstrained shape that is larger than the intended target vessel or simply different than a cross sectional profile of the intended vessel (i.e., not circular or tubular, but e.g., linear or other different shape). In such an example, as the shaped section is released from the delivery catheter, the shape section attempts to return to the unconstrained shape. In those variations where the unconstrained shape is different from the circular profile of the vessel, the leading wire assumes a shape that accommodates the vessel but is more rigid and stable since its unconstrained shape is entirely different from that of the vessel. In other words, the shaped section continually exerts an outward force on the vessel.
In yet another aspect, the shaped sections shown herein may not necessarily lie in the same plane. Instead, they can be axially spaced by an offset. One benefit of constructing the device to have non-planar shaped section is that the configuration might allow for delivery of the device through a smaller microcatheter because the shaped sections do not interfere with one another when collapsed to fit within the microcatheter.
Another aspect applicable to all variations of the devices is to configure the devices (whether the traversing filament or the surrounding portion) for better adherence to the obstruction. One such mode includes the use of coatings that bond to certain clots (or other materials causing the obstruction.) For example, the wires may be coated with a hydrogel or adhesive that bonds to a thrombus. Accordingly, as the device secures about a clot, the combination of the additive and the mechanical structure of the device may improve the effectiveness of the device in removing the obstruction. Coatings may also be combined with the capturing portions or catheter to improve the ability of the device to encapsulate and remove the obstruction (e.g., a hydrophilic coating).
Such improvements may also be mechanical or structural. Any portion of the capturing portion can have hooks, fibers, or barbs that grip into the obstruction as the device surrounds the obstruction. The hooks, fibers, or barbs 154 can be incorporated into any portion of the device. However, it will be important that such features do not hinder the ability of the practitioner to remove the device from the body.
In addition to additives, the device can be coupled to an RF or other power source (such as 14 or 16 in
The methods described herein may also include treating the obstruction prior to attempting to remove the obstruction. Such a treatment can include applying a chemical or pharmaceutical agent with the goal of making the occlusion shrink or to make it more rigid for easier removal. Such agents include, but are not limited to chemotherapy drugs, or solutions, a mild formalin, or aldehyde solution.
As for other details of the present invention, materials and manufacturing techniques may be employed as within the level of those with skill in the relevant art. The same may hold true with respect to method-based aspects of the invention in terms of additional acts that are commonly or logically employed. In addition, though the invention has been described in reference to several examples, optionally incorporating various features, the invention is not to be limited to that which is described or indicated as contemplated with respect to each variation of the invention.
An end 264 of the proximal capture portion 260 is affixed to a distal end of the sheath 106. However, as noted above, other variations are within the scope of the disclosure. The main bundle 202 can optionally terminate at a handle 242. As noted above, in certain variations, the main bundle is joined to a stiffer wire or stiffer bundle of wires. This allows the device 200 to have a very flexible distal section with a relatively stiffer proximal section.
The proximal end of the sheath 106 includes a sheath handle 244. As discussed herein, axial movement of the bundle 202 or proximal bundle 203 (typically at the handle 242) results in movement 126, or translation of the bundle within the sheath 106. This action moves the distal capture portion 226 (as shown by arrows 126). In certain variations, the device 200 is loaded into a microcatheter (not shown but discussed above) that is delivered to the site of the obstruction and crosses the obstruction.
In some variations, the sheath hub 244 includes one or more locking hubs 246. Where actuation (either axial or rotational) of the locking hub 246 locks the main bundle 202 relative to the sheath handle 244 and sheath 106. It follows that such locking action also locks the distal capture portion 226 relative to the proximal capture portion 260. A variety of methods can be employed to increase a frictional interference between the locking hub 246 and the proximal bundle 203. As a result, when a physician determines a length of an obstruction, the physician can set a spacing between the capturing portions 226 260 by locking the proximal bundle 203 relative to the sheath hub 244. Accordingly, the proximal bundle 203 can include any type of incremental markings to allow the physician to readily determine a spacing of the capturing portions. As illustrated, the sheath hub 244 can include additional injection ports to deliver fluid or other substances through the sheath 106.
As noted above, the device 200 can be used with micro-catheter. In those variations it is important that the device 200 is loaded without damaging the distal bundle 202, capture portions 226 260, and/or sheath 106. As a result, the device 200 can include an optional funnel 286 that reduces the proximal capture portion 260 (and/or the distal capture portion 226) for loading within the microcatheter and/or sheath 106.
Another variation of the device 200 includes an insertion tool 280 slidably affixed to the sheath 280. Because variations of the device 200 can be extremely flexible, the insertion tool 280 can be used to provide column strength to the sheath 106, bundle 202 or other components as the device 200 is pushed into the microcatheter. The insertion tool comprises a rigid section 282 and a frictional coupler 284. The rigid section 282 has a column strength that supports the device 200 to prevent buckling. The frictional coupler 284 can be a flexible material that allows an operator to squeeze or grip the coupler 284 to create a temporary frictional interface between the loading tool 280 and the device 200 (typically the sheath 106). Such an action allows axial advancement of the device 200 as the loading tool 280 is advanced into the microcatheter. Once the rigid section 282 is fully inserted into the microcatheter, the operator releases the frictional coupler 284 and can withdraw the loading tool 280 from the catheter without withdrawing the device 200. The insertion tool 280 can also include an optional loading tube 286 slidably coupled to the rigid section 282. When used, the funnel 286 can withdraw the proximal and distal capturing portion 226 260 within the loading tube 286. The loading tube 286 then couples to a microcatheter allowing the capturing portions to advance therein as the rigid section 282 and frictional coupler 284 advance the device 200 relative to the loading tube 286.
The funnel catheter 300 includes a first and second slotted funnels 330, 340 located at the distal end of an inner shaft 302. Each funnel 330 340 comprises a number of extensions or tines 332 342. The inner shaft 302 can be cut to produce the first tines 332. Alternatively, the first tines 332 can be affixed to a portion of the inner shaft 302. The second slotted funnel 340 is offset in both a proximal and rotational position relative to the first slotted funnel 330. The purpose of this dual offset is discussed in detail below. As shown, the second funnel 340 can be a slotted tube that is affixed over the inner shaft 302. In an alternate variation, a plurality of second tines 342 can be located about the inner shaft 302 to form a second slotted funnel 340. As shown in
Turning back to
As shown in
In some variations, the capturing portions discussed above can be constructed to improve their ability to be withdrawn into a guide sheath. For example, increasing the number of petals or flanges on the traversing sections increases the probability that the distal flanges nest within the proximal capturing portion. Alternatively, or in combination, the petals 238 on the distal capturing portion can be staggered in length or position to ease insertion into the proximal capturing portion. In another variation, the petals 238 shape or curvature can be adjusted so that they do not flare outward.
In another variation, a third distally located capture portion (similar to a distal capture portion) can be used to draw the retrieval device within a guide sheath. In such a variation, the third capture portion can be a larger distal capture portion and when the retrieval device engulfs an obstruction, the third basket portion can be proximally withdrawn to capture the retrieval device and obstruction.
As illustrated in
The mesh 370 can include any medically acceptable material such as a nitenol braid. Furthermore, the mesh allows for flow through the vessel or lumen while expanded. However, additional variations of the device can include a solid layer of material substituted for the mesh.
Various changes may be made to the invention described and equivalents (whether recited herein or not included for the sake of some brevity) may be substituted without departing from the true spirit and scope of the invention. Also, any optional feature of the inventive variations may be set forth and claimed independently, or in combination with any one or more of the features described herein. Accordingly, the invention contemplates combinations of various aspects of the embodiments or combinations of the embodiments themselves, where possible. Reference to a singular item, includes the possibility that there are plural of the same items present. More specifically, as used herein and in the appended claims, the singular forms “a,” “and,” “said,” and “the” include plural references unless the context clearly dictates otherwise.
It is important to note that where possible, aspects of the various described embodiments, or the embodiments themselves can be combined. Where such combinations are intended to be within the scope of this disclosure.